Brazing is a common method for joining metallic parts. Brazing involves applying a braze filler material, such as a braze paste or a braze foil, at an interface between two closely fitting parts, followed by heating of the braze filler to a temperature sufficient to cause the braze filler to form a braze liquid. The braze liquid may then distribute across the interface and wet the interface by capillary action. In some cases, the braze filler may be applied at one side of the interface and may be permitted to flow through the interface when melted. In such an arrangement, completion of wetting of the interface with the braze liquid may be confirmed by observation of the braze liquid at the other side of the interface. When suitably distributed across the interface, the braze filler liquid may then be cooled and hardened to provide a brazed joint between the two parts.
While effective, the formation of brazed joints is often limited to flat or straight connection interfaces between parts, as corners/sharp turns in the braze liquid flow path may interrupt the capillary movement of the braze liquid. The interruption of braze flow may ultimately hinder complete wetting of the interface between the parts, possibly leading to weak joints susceptible to failure during operation. Thus, joints with complex geometrical interfaces, such as shiplap joints, are currently a challenge to access by standard brazing techniques. However, shiplap joints are desirable in many applications as such joints have improved shear strengths relative to joints with flat connection interfaces. For example, U.S. Patent Application Publication Number US 2014/0248140 discloses the use of shiplap joints between stator elements of a stator assembly to provide a strong seal that counters gas loads on the stator vanes. Although the benefits of shiplap joints are well-recognized, workable methods for forming brazed joints at shiplap interfaces are still wanting.
Clearly, there is a need for strategies for providing brazed joints at complex geometrical interfaces, such as shiplap interfaces.